Occam's Razor: The overused observation that, all things being equal, the simplest solution tends to be the best one. I dislike the phrase "nowhere is this more true", but Occam certainly applies in spades to energy policy. My favourite example of simplicity triumphing over complexity is solar energy: solar water heaters are vastly more common than photovoltaic solar panels, because they are cheap, rugged, and extremely efficient. (No slander intended against the rapidly growing solar PV market.)
So I read with great interest a post by one of my favourite energy bloggers, Engineer-Poet, on running the entire United States on charcoal derived from biomass and crop wastes, while sequestering billions of tons of CO2 per year. It is an extremely detailed, very impressive bit of writing, that I won't hazard to summarize: If you're interested (and you should be) you should go read it.
I'll simply add that it would amuse me to no end if, after all the debates over hydrogen vs. ethanol, solar vs. wind, hybrids vs. biodiesel, we ended up fueling our society and saving the planet using a fuel that would have been common to our ancestors 600, or even 6,000 years ago. And, I suspect, Occam would chuckle with me.